Sunlight and food are rarely sufficient to enable individuals to maintain adequate vitamin D levels. For this reason, experts recommend that people consider taking nutritional supplements containing the vitamin.

Dr. Arnold Moses, a professor of medicine at SUNY Upstate Medical Center, told the Syracuse Post-Standard that lifestyle-related vitamin D deficiency goes back to Roman times. He said that when people began moving into cities where smog clouded the skies and where work was predominantly done inside, they started experiencing symptoms of vitamin D deficiency.

One of the best sources of the nutrient is sun exposure. The skin is able to turn the rays from the sun into vitamin D. However, few people spend adequate amounts of time outdoors due to their job and other lifestyle factors.

Due to these circumstances, Dr. Moses said that many people should consider taking nutritional supplements containing vitamin D, particularly if they have been diagnosed by a doctor has having low levels of the nutrient.

The Institute of Medicine recommends that healthy adults consume 600 international units of vitamin D each day, though experts have suggested this may be too low.